as you go down the group - the lower the reactivity, the higher the MP and BP and the higher the density

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what is the trend in group 7?

they all have 7 electrons in their outer shell - they become less reactive becausethe outer shell gets further away from the nucleus so another electron isn't so easily gained.

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what happens in displacement reactions?

a more reactive halogen will displace a less reactive one.

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why do group 1 and group 7 elements easily react?

because group 1 elements are trying to get rid of one electron and group 7 elements are trying to gain a electron

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what are the properties of group 1 and group 7 compounds?

they conduct electricity when molten or dissolved because they're made up of charged particles called ions, which are free to move around. also these compounds form crystals because they are arranged in a regular lattice

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what are ions?

atoms which have lost or gained an electron meaning they have a charge as the number of protons and electrons is not equal

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what is ionic bonding?

when electrons are transferred from one atom to another. atoms which lose electrons = positive ions, atoms which gain electrons = negative ions